1. Field of the Invention
The present invention relates to a bearing specifically adapted to securing to the fuselage of an aircraft, a single wing having an adjustable feature. More particularly, this invention relates to a bearing which facilitates rotations of this wing about an axis which is normal to the plane of the wing so as to permit adjustament of the angle of the wing with respect to the aircraft fuselage.
2. Background
Aircraft employing adjustable, variable sweepback wings are well known. Such adjustable sweepback wings provide a proven solution to problems encountered when such aircraft progress from the transonic to the supersonic region of flight. The oblique wing designed aircraft, comprising a single, adjustable yawed wing, potentially offers the same advantges as its swept wing counterpart while at the same time improving aircraft efficiency between transonic and supersonic flight. This is a direct result of the high lift-to-drag ratio achieved in the cruise mode when the wing is in the yawed position. In addition, the high aspect ratio available with the wing in the unyawed position provides excellent landing and takeoff characteristics for this type of aircraft.
To accomplish the adjustment of the angle of the wings with respect to the aircraft's fuselage, bearings are normally provided which secure the wings to the fuselage. Various bearings have been devised to accomplish these required adjustments and have usually featured either spherically shaped bushings or a combination of sleeve and roller type bearings.
Regardless of the type of bearing employed for this application, it must carry a variety of loads ranging from those encountered during supersonic flight to those encountered when the aircraft is stationary. In addition, the bearing must be failsafe and possess those characteristics required for any aircraft use; namely lightness and ease of maintenance.
The present invention provides solutions to these requirements. It has demonstrated an ability to perform when subject to bearing stress loads of 50,000 pounds per square inch. Due to its dovetail groove and circular shape, the bearing is inherently failsafe since any failure of one of the bearing sides results in the load being carried by the remaining bearing side. The simplicity of bearing design as well as the existence of a minimum number of elements required for the assembly of the bearing promotes lightness and ease of maintenance. Finally, the bearing provides an adjustment feature which compensates for wear incident to normal bearing operation.
The dovetail groove is not new, having been shown by Poplinski, U.S. Pat. No. 3,498,685. Although this patent shows a bearing with a cross-section similar to the present invention, the Poplinski invention is distinguishable in that it is linear in shape, not circular, and hence is non-redundant. The present invention obtains its inherent redundancy due to the use of a dovetail groove in a circular shape. Finally, the Poplinski invention does not provide the adjustment feature of the present invention.
Lonngren, et al., U.S. Pat. No. 3,517,975, have shown a circular bearing similar in shape to the present invention. That patent, however, is directed to roller bearing construction and does not employ the dovetail groove as the bearing surface as does the present invention. In addition, that invention lacks any adjustability feature needed to compensate for normal bearing wear.